"""Command-line interface for CSV data analysis tool."""

import argparse
import sys
import os
from typing import List, Optional

from loader import CSVLoader
from analyzer import DataAnalyzer
from reporter import ReportFormatter


def parse_arguments():
    """Parse command-line arguments."""
    parser = argparse.ArgumentParser(
        description="CSV Data Analysis Tool - Comprehensive statistical analysis of CSV files",
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog="""
Examples:
  python cli.py --file data.csv
  python cli.py --file data.csv --output report.txt
  python cli.py --file data.csv --columns age,salary,score
  python cli.py --file data.csv --filter "age > 25" "salary >= 50000"
  python cli.py --file data.csv --columns age,salary --filter "age > 18" --output analysis.txt
        """
    )
    
    parser.add_argument(
        '--file', '-f',
        type=str,
        required=True,
        help='Path to the CSV file to analyze'
    )
    
    parser.add_argument(
        '--columns', '-c',
        type=str,
        help='Comma-separated list of columns to analyze (default: all columns)'
    )
    
    parser.add_argument(
        '--filter',
        type=str,
        nargs='+',
        help='Filter conditions (e.g., "age > 25" "name contains John"). Supported operators: ==, !=, >, >=, <, <=, contains'
    )
    
    parser.add_argument(
        '--output', '-o',
        type=str,
        help='Output file path for the report (default: print to console)'
    )
    
    return parser.parse_args()


def validate_arguments(args):
    """Validate command-line arguments."""
    # Check if file exists
    if not os.path.exists(args.file):
        print(f"Error: File '{args.file}' not found.")
        sys.exit(1)
    
    # Validate file extension
    if not args.file.lower().endswith(('.csv', '.txt')):
        print("Warning: File does not have a .csv extension. Proceeding anyway...")
    
    # Parse columns if provided
    columns = None
    if args.columns:
        columns = [col.strip() for col in args.columns.split(',') if col.strip()]
        if not columns:
            print("Error: Invalid columns specification.")
            sys.exit(1)
    
    # Validate output path
    if args.output:
        output_dir = os.path.dirname(os.path.abspath(args.output))
        if not os.path.exists(output_dir):
            print(f"Error: Output directory '{output_dir}' does not exist.")
            sys.exit(1)
    
    return columns


def main():
    """Main function to orchestrate the analysis pipeline."""
    try:
        # Parse and validate arguments
        args = parse_arguments()
        columns = validate_arguments(args)
        
        print("CSV Data Analysis Tool")
        print("=" * 50)
        
        # Initialize loader
        loader = CSVLoader()
        
        # Load CSV file
        print(f"Loading file: {args.file}")
        try:
            df = loader.load_csv(args.file, columns=columns)
        except Exception as e:
            print(f"Error loading CSV file: {e}")
            sys.exit(1)
        
        # Apply filters if specified
        if args.filter:
            print(f"Applying filters: {args.filter}")
            try:
                df = loader.apply_filters(df, args.filter)
                if len(df) == 0:
                    print("Warning: All rows were filtered out. No data to analyze.")
                    sys.exit(0)
            except Exception as e:
                print(f"Error applying filters: {e}")
                sys.exit(1)
        
        # Initialize analyzer
        print("Performing statistical analysis...")
        analyzer = DataAnalyzer(df)
        
        # Run analysis
        try:
            analysis_results = analyzer.run_full_analysis()
        except Exception as e:
            print(f"Error during analysis: {e}")
            sys.exit(1)
        
        # Generate report
        print("Generating report...")
        try:
            formatter = ReportFormatter()
            report_text = formatter.generate_report(
                analysis_results=analysis_results,
                file_path=args.file,
                filters_applied=args.filter
            )
        except Exception as e:
            print(f"Error generating report: {e}")
            sys.exit(1)
        
        # Output report
        if args.output:
            try:
                formatter.save_report(report_text, args.output)
                print(f"\nAnalysis complete! Report saved to: {args.output}")
            except Exception as e:
                print(f"Error saving report: {e}")
                sys.exit(1)
        else:
            print("\n" + "=" * 50)
            print(report_text)
        
        # Print summary
        basic_info = analysis_results.get('basic_info', {})
        print(f"\nSummary:")
        print(f"  Rows analyzed: {basic_info.get('total_rows', 'N/A'):,}")
        print(f"  Columns analyzed: {basic_info.get('total_columns', 'N/A')}")
        
        if args.filter:
            print(f"  Filters applied: {len(args.filter)}")
        
        outliers = analysis_results.get('outliers', {})
        total_outliers = sum(info.get('outlier_count', 0) for info in outliers.values() 
                           if isinstance(info, dict) and 'outlier_count' in info)
        if total_outliers > 0:
            print(f"  Total outliers detected: {total_outliers}")
        
        correlations = analysis_results.get('correlations', {})
        if isinstance(correlations, dict) and 'strong_correlations' in correlations:
            strong_corr_count = len(correlations['strong_correlations'])
            if strong_corr_count > 0:
                print(f"  Strong correlations found: {strong_corr_count}")
        
        print("\nAnalysis completed successfully!")
        
    except KeyboardInterrupt:
        print("\nOperation cancelled by user.")
        sys.exit(0)
    except Exception as e:
        print(f"Unexpected error: {e}")
        sys.exit(1)


if __name__ == "__main__":
    main()